(a) Opinion and reputation evidence of character. - The
credibility of a witness may be attacked or supported by evidence in the form
of reputation or opinion as provided in Rule 405(a), but subject to these
limitations: (1) the evidence may refer only to character for truthfulness or
untruthfulness, and (2) evidence of truthful character is admissible only after
the character of the witness for truthfulness has been attacked by opinion or
reputation evidence or otherwise.

(b) Specific instances of conduct. - Specific instances of the
conduct of a witness, for the purpose of attacking or supporting his
credibility, other than conviction of crime as provided in Rule 609, may not be
proved by extrinsic evidence. They may, however, in the discretion of the
court, if probative of truthfulness or untruthfulness, be inquired into on
cross-examination of the witness (1) concerning his character for truthfulness
or untruthfulness, or (2) concerning the character for truthfulness or
untruthfulness of another witness as to which character the witness being cross-examined
has testified.

The giving of testimony, whether by an accused or by any other witness,
does not operate as a waiver of his privilege against self-incrimination when
examined with respect to matters which relate only to credibility. (1983, c. 701, s. 1.)